This is the first in a series of articles about how our minds work, aimed at better understanding how to facilitate faster and more graceful cultural change. Please see Taking Einstein Seriously for an overall introduction.

The conscious part of our minds, the place where our attention is focused, is at the heart of all of our learning and high-level mental functioning. It is, in computer terms, our “central processing unit.”

Supporting this central part of our minds is what psychologists call “working memory,” which holds the immediate content that we work on through conscious thought.

Working memory can also be described as the “chunks” of information that can be kept simultaneously in an easily retrievable state in our minds. Working memory is critical for language comprehension, problem solving, planning and similar high-level mental functioning.

Its characteristics, and especially its limitations, are so familiar to us that we hardly notice, yet it has profound implications for the way we think. The main take-away is that when we are attempting any kind of high-level mental functioning that involves considering or comparing more than about four chunks of information at a time, we need the help of external memory aids, like written material and drawings on paper or computer screens. This impacts everything from meetings to presentations to conversations to personal creative work — all of which in turn are part of cultural change.

Each chunk can come from new experience via short-term memory or via recall from long-term memory, like this:

When dealing with topics that are already familiar to us, we are able to quickly swap relevant chunks of information between working memory and long-term memory, and this gives the impression that we have an expanded working memory. However, the same limit of four or so chunks still applies and becomes apparent as soon as we encounter unfamiliar topics.

The limitation of four or so chunks at a time has major implications for our ability to do any kind of high-level mental function “in our heads,” that is, without the aid of external tools like paper or computers screens.

Here’s an example you can use to directly experience this yourself. The following audio clip contains four numbers, each with four digits. Listen to the clip, try to remember the numbers and then add the numbers in your head without writing anything down. Most people will find it impossible to do this. Those who can do it, usually do so with the help of great concentration — much more attention than we apply in our ordinary activities.

Next, listen to the clip again, but this time write the numbers down. Once you have all four, add them up on paper. Most people will find this a doable task, even if it is tedious.

Here is how our minds work when we have the aid of paper (this is a different set of numbers):
When we get to the 6 in the first column, all we have to do in our minds is add 7 (the result that we are holding in our working memory from having just added 2 and 5 in a previous step) to 6 and then hold the new result (13) as we move down to the 3. At each step of the way, all we need to hold in our working memory are three numbers: the result from the previous step, the number we are now looking at, and the new result from those two. Using this procedure, which is simple at each step of the way, we could add a tall column of large numbers. The paper serves as our external working memory and allows us to go way beyond what we could do in our heads without any external help.

The limitation of four or so chunks at a time, combined with our ability to call up new chunks by association from long-term memory means that our thinking process happens in long associational chains. Our thinking is like a trail or road through the landscape of thought — narrow at each moment of time but able to cover a long distance from start to finish. That’s great for storytelling but not so good for multi-faceted creative problem solving or thinking outside of our habitual grooves of thought.

The limits of working memory also have major implications for anyone who is attempting to deal with any situation where more than three or four factors need to be considered. This is true whether we are working on our own or trying to communicate to others, whether in a presentation, a meeting or a conversation. Don’t expect to be able to do this well without external memory aids. This is one of the key reasons why discussion-oriented meetings are often so unproductive.

There are useful techniques for working around these limitations (see, for example, “Visual Meetings: A Revolution in Group Productivity”), but this article is not the place to go into them. The key point here is that if we want to do the kind of high-level mental activity required to address the challenges of our times, we need to work around the limits to “in the head” thinking imposed by our limited working memory.

Please note, the definitions of “short-term memory” and “working memory” are not standardized, and some psychologists use them interchangeable. Regardless of the terminology, the essential point is that the limit of four or so chunks at a time profoundly influences the character of our thinking process.